Gradient structured polyethylene composites with enhanced thermal conductivity, dielectric and mechanical properties

In view of the diversified requirements for polymer-based composites in modern electronic devices and electrical systems, a great challenge has to be faced in realizing the simultaneous enhancement of thermal-electrical-mechanical properties. Herein, we designed the gradient structured composites by building polyethylene (PE) based composites with different Al2O3 contents and optimized the properties by adjusting the distribution of temperature, electric and stress fields. The composites with double-layered gradient structure achieves superior through-plane thermal conductivity of 0.65 W/(m·K), high breakdown strength of 94.2 kV/mm and good tensile strength of 10.1 MPa, revealing an increase of 25%, 10% and 9% compared to the traditional Al2O3/LLDPE composites, respectively. Finite element simulation provided favorable evidences for the action mechanism on gradient structure regulating temperature and electric field. The strategy of constructing gradient structure provides a feasible route to meet the comprehensive performance requirements of PE based composites in massive manufacture scenario for practical insulation applications.